Image-processing technology has already begun to be applied to surveillance systems intended to detect the intrusion of unwanted persons and/or the occurrence of unusual events, and to vehicle-mounted systems for assisting safety driving of vehicles. For outdoor image-processing systems such as vehicle-mounted systems, camera control matching a particular external environment is needed to acquire necessary images from one image pickup device into multiple application programs. Even for a single application program, the need arises for a user to control the direction and exposure of the camera according to the desired viewing place and/or the desired operating time zone. For example, in the camera system mounted in an automobile to recognize lanes, the brightness of the images obtained will abruptly change according to the particular environmental conditions. For example, the object to be photographed may be present at the entrance/exit of a tunnel, exposed to the sunlight in the late afternoon, or exposed to the headlight(s) of an oncoming vehicle. Even in such cases, the camera system must recognize lanes stably with one camera installed in a forward direction. Exposure control techniques for acquiring stably the images that an application program requires are disclosed in, for example, Japanese Patent Laid-Open No. Hei 8 (1996)-240833 and Japanese Patent Laid-Open No. Hei 9 (1997)-181962.
To proliferate the application of image-processing technology to these systems, image-processing apparatus is required to be reduced in installation space requirements and in price. The techniques exist that each share one image pickup device between multiple application programs in order to achieve such space requirement reduction and price reduction. An example of such a technique is, as disclosed in Japanese Patent Laid-Open No. Hei 7 (1995)-46568, enables multiple application programs to use one camera efficiently. More specifically, multiple application programs share one camera when sharable images can be acquired using the same camera control parameters (exposure, viewing angle, and camera direction) that the multiple application programs require. One camera is also shared under the conditions that any differences in each of the above camera control parameters stay within a required range and that time-division control is possible by modifying data settings within a very short time during which the images in the multiple application programs are not interrupted. If any differences in each of the above parameters overstep the required range, the corresponding application programs will be notified of the fact that photographing is impossible, and appropriate processing will be executed at the corresponding application program side.